Propeller



S. HEATH PROPELLER Apxr: 28, 1931.

Filed Dec.

31, -1925 3 Sheets-Sheet. 2

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S. HEATH April 28, 1931.

PROPELLER Filed Dec. 3l, 1925 5 SheetsfSheet. 3

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Patented Apr. 28, 1931 UNITED STATES PATENT OFFICE! SPENCER HEATH, OF ELKRIDGE, MARYLAND, ASSIGNOR T THE PROPELLEB COMPANY, OF BALTIMORE, MARYLAND, A CORPORATION O'F MARYLAND PRJOPELLER Application lled December 31, 1925. Serial No. 78,659.

Thispinvention relates generall to pI'O- pellers for aircraft and particular y to propellers having met-al blades.

One object of my invention is to provlde a propeller in which the blades are hinged or ivotally connected to the hub. It has been ibund that propeller bladesniade 0f metal very frequently fail or break due to crystal.- ization or fatigue of the metal near the hub which results from the constant flexing of the metal caused by the intense vibration of the blades. By providing a hinge or pivotal connection between the blade and hub, the vibrations of the blade are absorbed in the hin e and the flexing of the metal in the blades is thus obviated.

. A further object of my invention is to provide a construction in which the axes of the hinges between the blades and hub are arranged obliquely to the plane of rotation of the propeller. This arrangement simplifies the forming of the blades b reducing the amount of twist which must e given to the metal, and it, furthermore, serves to reduce the end thrust on the hinges due to the torque l of the engine or propeller shaft.

Another. object of my invention is to provide a construction in which the axes of the hinges between the blades and hub may be angularly adjusted relative to the plane of rotation of the propeller blades and secured in any desired osition of adjustment.

A further object is to provide a hinge connection between the hub and blad which will permit a slight degree of pivotal or hinge c action without any sliding friction `between the parts.

A still further object is to provide yieldable means for maintaining the blades in a substantially radial position while the propeller is at rest.

A still further object is to provide a strong and rigid construction for the inner or base portion of the blades and also to provide detailed improvements in the. hinge conneclion between the base of the blades and the A still further object is to provide certain improvements in the construction of the blades themselves.

The objectsand advantages of m invention will be more fully understood rom the following specification and the accompanying drawings forming a part thereof and in which one specific embodiment of the invention is disclosed, it bein obvious that changes and modifications in t is construction may be made within the spirit of the invention. In the accompanying drawings:

Figure l is a front elevation of a propeller embodying my invention, the ends of the blades being cut away, l

Figure 2 is a transverse section on the line 2 2 of Figure l,

Figure 3 is a longitudinal section on the line 3 3 of Figure Figure 4 is a longitudinal section on the line 4 4 of Figure 2,

Figure 5 is a longitudinal section showing a double-walled one piece type of blade,

Figure 6 is a transverse section of the blade shown in Figure 5,

Figure 7 is a detailed section showing one of the spacing and securing devices employed between the walls of the double-walled blade,

Figure 8 is a fragmentary longitudinal section substantially on the line 8 8 of Figure 3 showing certain details of the hinge constructions,

Figure 9 is a View similar to Figure 8, showing a somewhat modified construction,

Figure 10 is another view similar to Figure 8 showing a further modified construc tion,

Figure 11 is an elevational view of a modiiied form of blade having the body thereof formed with a single wall, and

Figure 12 is a longitudinal section on the line 12 12 of Figure l1.

Referring to the drawings in detail by the reference characters thereon, A indicates an engine shaft on which the propeller is mounted. The hub of the propeller is preferably formed of an inner member 10 and outer members 10A, the former being rigid-` ly connected to the engine shaft A and the latter carry the blades 11, any desired number of which may be employed. The 'inner member l0 of the hub is provided with externally threaded reduced portions 10B and the outer members 10A are provided with socket (portions 10C, similarly threaded, and adapte to be screwed down over the threaded portions 10B. By this arrangement, it is evident that the outer members 10A of the hub may be rotated or angularly adjusted relative to the inner member 10. To secure the outer members 10A in any desired position of adjustment relative to the member is adapted to cover any space left between' the inner ends of the socket portions 10C and the adjacent portions of the inner member 10. The bands 10D are accurately positioned on and are movable with the sockets 10C by means ofkeys K so that the space between the ears of the bands will always lie opposite the slots 10F. The flanges 10G are preferably marked with graduations 10H for accurate setting or positioning of the blades.

The blades 11 are hingedly or pivotally connected to the members 10A of the hub by the arrangement now to be described. Each member 10A is provided with two outwardly projecting spaced hinge knuckles 12 having aligned openings 13 for receiving a hinge pin. The inner or base portion of each blade 11 is provided with two slots 14 spaced to correspond to the distance between the inner Walls of said-knuckles 12 and of a width substantially equal to the thickness thereof. The two slots 14 produce three spaced ears or arms 15 on each blade, the

central one of which is adapted to lie be- Yen tween the two knuckles 12 and the outer ones adapted to lie against the outer surface of the knuckles 12. The arms or ears 15 of the blades are also rovided with aligned openings corres on ing to openings 13 in the ears 12. A inge pin 16 is inserted through the openings in the knuckles 12 and ears 15, this pin having washers 16A at each end and also having a nut 16B threaded on one end thereof for holding it in place.v Preferably hardened bushings 17 are arranged in the knuckles 12 around the hinge pin 16, these bushings preferably having a tight fit on the pins 16 but being free to rotate' in the openings 13.

' In the drawings, the engine shaft A is assinned to be horizontal, member 10 which is perpendicular to and extends radially from shaft A is shown in a vertical position, and hinge pin 16 is shown in a horizontal position. Hinge pin 16 is illustratedl in a substantially symmetrical position with respect to .member 10 and to blade 11, and it is obvious that a vertical line extending radially from the axis of the engineshaft would lie at right anglesto hinge pin 16 and intersect it at substantially its middle.

From the construction thus far described, it is evident that the axes of the hinge pins 16 can be adjusted relative to 'the plane of rotation of the propeller blades, this being accomplished by the angular adjustment of the outer members 10A of the hub relative to the inner member 10. Normally the axes of the hinge pins 16 are arranged obliquely to the plane of rotation of the blades. This arrangement, as previouslynoted, reduces the amount of twist which must be given to the metal in forming the blades and it has the additional advantage of reducing the end 'thrust on ihe hinges which results from the torque applied by the engine shaft. This is an important feature because the torque applied to the propeller is not constant but intermitf. ent due to the successive impulses from the motor.

lVith the blades hinged tothe hub as previously described, it will be understood that while the propeller is running, the centrifugal force, which is very great, will serve to maintain the blades in a radial or operative position. To prevent the blades from falling over or about their hinges when the propelleris at rest, I provide the following arrangement. Each blade adjacent its base has secured thereto a plate 18 the end portions of which form projections extending laterally on each side of the hinge pin 16, the central portion of said plate being bent to conform to the curved portion of the blade surrounding the pin. The plate 18 is preferably secured to the blade by means of spring clamping arms 18A welded to the plate 18 and so arranged as to closely embrace the base of the blade. Beneath each end of said plate 18 is arranged a resilient member 19, which may be pads of rubber, coiled springs or any other suitable device. The members 19 are preferably attached to the underside of said'plate, in any desired manner. 19 are preferably spaced a slight distance from the bottom of the recess in which they are placed, as indicated at 18B. mits slight pivotal motion of the blades about the pins 16 without com ression of the members 19, but when the b ades are at rest the arrangement described will hold the blades substantially in a radial position.

With the blades hinged to the hub as 'dc-I.

scribed it is important that the hinge pins be permitted a limited amount of pivotal movement relative to the ears 12 without any The lower surfaces of the members out sliding contact.

sliding contact between the parts because such sliding frictional contact may cause the contacting surfaces to gall andseize thus stiening or rendering inoperative the hinge connection and leaving the blades subject to rapid lieXing near the hub with result-ant fatigue and fracture of the metal after a short time. To accomplish this resultl and insure a slight degree of flexibility at the hinge at all times I provide vthe variousarrangements illustrated in FiguresV 8, 9 and l of the drawings. It `will be understood that the hinge pin 16 is preferably lixed in the ears at the base of the blades 11. Therefore, in order to take up the vibrations of the blade, the pins 16 must be capable of slight rotation relative to the knuckles 12 on lthe hub without sliding contact between these parts. In the form shown in Figure 8 this is accomplished by simply making the openings 13 in the knuckles 12 slightly larger than the pin 16 and the bushings 17`surrounding the same. The space or clearance between the bushing and the wall of the openings 13 is shown at 21. It is evident that this arrangement will permit a slightdegree of rolling motion of the pin 16 and the bushing 17 in the opening without any sliding friction between the p arts. In the form shown in Figure 9, the'pin 16 is also made slightly smaller than the openings 13 and provided with an angular or knife-edge p0rtion 22 which is adapted to bear against the inner wall of the openings 13. This arrangement also permits slight rolling action of the pin 16 relative to the knuckles 12 with- In Figure 10, the openings in the knuckles 12 are provided with ball or roller bearings 23 which are adapted to receive the thrust of the hinge pin 16 and permit rotation` of the same vrelative to the knuckles 12 without sliding contact.

It will thus be seen that the construction illustrated in Figs. 8 and ..9 will permit a limited rolling action of the pins .16 in the openings 13 without any sliding` contact taking place between thep'arts. This limited rolling action will servefto s. take` up the limited arid yrapid vibrations of the.. blades and thus any danger of the hinges seizing or becoming rigid is obviated. The construction shown in Fig. 10accomplishes the same result b obviatin any danger of sliding rictiona contact and the knuckles 12. Y In yaddition to the features heretoforedescribed, my invention contemplates certain detailed improvements 'in the construction of theblades which render them specially applicable to my hinged-blade propeller. In Figs. 1 to 10 inclusive of the drawings there are shown one piece blades havin double-walls, the detailed construction o this :formA of blade being more fully illustrated in Figs. 5, 6 and 7. InFigs. 11 and 12 etween the pins 16 a single wall blade is shown, that is one formed of a single piece but of single thickness only.

. In forming the double-wall blade, I preferably employ a single piece of sheet mate- Y rial longer than the length of the blade to be produced. The material is tapered from the center toward each end and from one edge toward the other. The width of the sheet at various points from the center toward each end is such as to produce a blade of the desired width. The sheet thus formed is bent at its center 11A, Fig. 5, and the edges of the overlying stralght portions 11B are welded or 'otherwise secured together, as indicated at 11C. The portions 11B are, of course, given the desired twist and contour before being bent upon each other which may be done by pressing or in any other suitable manner. In order that the walls 11B of this form oi blade may be properly spaced and also held against separation, a plurality of threaded studs 11D are threaded through one of the walls 11B and these studs are provided with reduced ends 11E which are adapted to project through countersunk holes in the opposite wall 11B and be riveted over. This arrangement eliectively prevents collapse or .separation of the spaced walls 11B. It will be understood that the bent portion-11A of this form of blade is shaped to closely lit the hinge pin 16 and also that the base of the yinished blade is provided with the slots 14 and ears 15, as previously described.

The single-wall blade illustrated in Figs.'-

11 and 12, is formed of a single piece of suitably shaped metal which preferably tapers from base to tip and from the back to the front and bent to roduce the desired twist.

Whether forme of single wall or double wall, the basal portion of the blade is preferably held between the arms of a hinge loop 24 the middlexportionof which is slotted to receive the hub knuckles l2. Thearms kof the hinge loop 24 are `secured .-to4 the front and back sides. of the blade-bases preferably by welding or'brazing indicated at 25. :In

connection with the double wallpblade the 1. A. propeller having a hub provided with v, outwardly pro'ectin 4knuckles, a blade hav-.

ing slots at its ase or receiving said knuckles, and a hinge 'pin passing through said the hinge pin, only knuckles and through the base of the blade, whereby the blade is hingedly connected to the hu 2. A propeller blade structure in which the blade is formed of a sheet of material transversely bent intermediate its ends and its two unbent portions being brought together and secured to each other to form the opposite sides of the blade, and a loop embracing the base of the blade, the ends of the loop being secured to the sides of the blade.

3. In a propeller, in combination, a hub, a blade, a hinge pin for connecting said` hub and blade, and' means for connecting said pin to the hub and blade, to roll slightly upon one of said parts upon slight rotation of the blade about the axis of the pin.

t. In a propeller, in combination, a hub and a blade connected by a hinge pin, said pin tightly engaging one of said parts, the other of said parts having openings slightly larger than said pin, whereby the pin may roll slightly on said last named part upon slight rotation of the blade about the axis of said pin.

5. In a propeller, in combination, a hub having spaced hinge knuckles thereon provided with aligned openings, a blade having an ear arranged between said knuckles, a hinge pin mounted in said openings and passing through said ear, said pin being slightly smaller than said openings, to permit slight rolling motion of the pin relative to said knuckles.

6. In a propeller, `in combination, a hub having spaced hinge knuckles thereon provided with aligned openings, a blade having an ear arranged between said knuckles, a hinge pin mounted in said openings and passing through said ear, said pin being slightly smaller than said openings and having an angular portion adapted to bear against the inner wall `of said openings, whereby slight vrolling motion of said pin relative to said knuckles is permitted.

7. In a propeller, the combination of a hub, a hinge pin mounted thereon, and a blade swingable around the axis of said hinge pin comprising a sheet of metal bent around said hinge pin and forming opposite side portions l of said blade.

8. In a propeller-,the combination of a hub, a hinge pinmounted thereon, a blade swing- -able around the axis of said hinge pin comprising a sheet of metal bent around said hinge pin, and a sheet metal reinforcing member bent around said hinge pin and embracing both sides of the innerportion of said blade.

9. In a propeller, the combination of a hub having hinge portions, a hinge pin connected to said hinge portions, and a blade swingable around the axis of said hinge pin comprising a sheet of metal bentdaround said hinge pin, and a sheet metal reinforcing member bent around said hinge pin and embracing both sides of the inner portion of said blade, the inner end of said blade and said reinforcing member being slotted to rcceive the co-acting hinge portions on the hub.

10. In a propeller, the combination of a hub, a hinge pin mounted thereon, a blade swingable around the axis of said hinge pin, and a sheet metal member bent around said `hinge pin and embracing both sides of the hub portion of said blade.A

l1. In a propeller, the combination of a hub having hinge portions, a hinge pin connected to said hinge portions, a blade swingable around the axis oi said hinge pin, and a sheet metal member bent around said hinge pin and embracing both sides of the hub portion of said blade, the inner end of said sheet metal member being slotted to receive the co-acting hinge portions on the hub.

l2. In a propeller,a hub adapted to receive a propeller shaft, a hinge pin carried by said hub at right angles to and intersected by a line extending radially from the axis of the propeller shaft, said hinge pin being arranged to be fixed obliquely to the pla-ne of rotation of the propeller at an angle which is constant'for all speeds of rotation of said hub, and a rigid blade swingable about the axis of said hinge pin.

13. In a. propeller, a hub adapted to receive a propeller shaft, a hinge pin carried by said hub at right angles to and intersected at substantially its middle by a line extending radially from the axis of the propeller shaft, said hinge pin being arranged to be fixed obliquely to the plane of rotation of the propeller at an angle which is constant for all speeds of rotationof said hub, and a rigid blade swingable about the axis of said hinge pin. A

14. In a propeller, a hub adapted to receive a propeller shaft, a hinge pin carried by said hub at right angles to and intersected by a line extending radially from the axis of the propeller shaft, said hinge pin being arranged to be lixed obliquely to the plane of rotation of the propeller at an angle which is constant for all speeds of rotation of said hub, means for selectively adjusting the angle of Obliquity of said hinge pin, and a rigid blade 4swingable about the axis of said hinge pm..

15. In a propeller a hub adapted to receive 16. In a propeller, a hub adapted to receive a propeller shaft, a 4hinge pin carried by said hub at right angles to and intersected by a line extending radially from the 5 axis of the propeller shaft, said hinge pin being `arranged to be fixed obliquely Vto the plane of rotation of the propeller shaft at an an le which is constant for all speeds of rotatlon of said hub, a-rigid blade swingable lo about the axis of said hinge pin, and resilient means for preventing the blade from moving out of a substantially radial position.

- 17; 'In a propeller,V the combination with a hub and a blade hinged thereto, of a resilient member on one side of the hinged connection i and-adapted to he compressed by a movement of the blade in the direction of said member and away from a radial position, said blade having a slight freedom of pivotal 20 movement without compressing said resilient member.

.18. In a ro eller, the combination with a hub and a bla e hinged thereto, of4 a pair of resilient members one on eachside of the *hinged connection, each of said resilient members being adapted to be compressed by a movement of the blade in the direction of said member and away from a radial position, said blade having a slight freedom of piv- 3o otal movement without compressing either of said resilient members.

19. In a ro eller, the combination with a hub and a la e hinged thereto, of a plate mounted on said blade and extendinl lateral e5 ly from each side of the inner end t ereof, a resilient member interposed between each end of said plate 'and said hub, each of said resilient members being adapted to be compressed by a movement of the blade in the di- 40 rection of said member and away from a radial position, said blade havin a slight A freedom of pivotal movement wit 'out compressing eitherof said resilient members.

. In testimony whereof I hereunto aix my signature.

`srENoim HEATH. i 

